The present invention relates generally to fuel injectors of the type that are used to inject liquid fuel into the air induction system of an internal combustion engine and particularly to a fuel injector with multiple orifice plates and an atomizer that fits over the nozzle of such a fuel injector and serves to convey assist air to the orifice plates to promote the atomization of the injected liquid fuel that has just left the nozzle.
Air assist atomization of the liquid fuel injected from the nozzle of a fuel injector is a known technique that is used to promote better preparation of the combustible air/fuel mixture that is introduced into the combustion chambers of an internal combustion engine. A better mixture preparation promotes both a cleaner and a more efficient combustion process, a desirable goal from the standpoint of both exhaust emissions and fuel economy.
Air assist atomization technology is known. The technology recognizes the benefits that can be gained by the inclusion of special assist air passages that direct the assist air into interaction with the injected liquid fuel. Certain air assist fuel injection systems use pressurized air, from either a pump or some other source of pressurization, as the assist air. Other systems rely on the pressure differential that exists between the atmosphere and the engine""s induction system during certain conditions of engine operation. It is known by the inventors to mount the fuel injectors in an engine manifold or fuel rail which is constructed to include assist air passages for delivering the assist air to the individual injectors.
It is known to construct an air assist atomizer in which the definition of the final length of the assist air passage to each fuel injector tip is provided by the cooperative organization and arrangement of two additional parts which form an atomizer assembly disposed between the nozzle of an injector and the wall of a socket that receives the injector. One advantage of that invention is that it adapts an otherwise conventional electrically-operated fuel injector for use in an air assist system without the need to make modifications to the basic injector, and without the need to make special accommodations in the injector-receiving socket other than suitably dimensioning the socket to accept the air assist atomizer.
Briefly, the present invention provides a fuel injector. The fuel injector includes a housing having an inlet, an outlet a longitudinal axis extending therethrough, and a seat disposed proximate to the outlet. The seat includes a sealing surface and a passage extending therethrough. The fuel injector also includes a needle being reciprocally located within the housing along the longitudinal axis between a first position wherein the needle is displaced from the seat, allowing fuel flow past the needle, and a second position wherein the needle is biased against the seat, precluding fuel flow past the needle. The fuel injector also includes a multi-layer orifice plate assembly located at the housing outlet. The orifice plate assembly includes a first orifice plate having a plurality of first openings extending therethrough and a second orifice plate disposed proximate the first orifice plate. The second orifice plate includes a first face having a perimeter, a wall generally extending from the first face and circumscribing the perimeter, and a plurality of channels extending radially therethrough from the longitudinal axis toward the perimeter. The second orifice plate also includes a second face disposed opposite the first face and a plurality of second openings extending between the first face and the second face. The fuel injector also includes an air assist sleeve disposed about the housing proximate the outlet. The air assist sleeve includes at least one air channel in communication with the plurality of channels.
The present invention also provides a fuel injector comprising a housing having an inlet, an outlet, a longitudinal axis extending therethrough, and a seat disposed proximate the outlet. The seat includes a sealing surface and a passage extending therethrough. The fuel injector also includes a needle reciprocally located within the housing along the longitudinal axis between a first position wherein the needle is displaced from the seat, allowing fuel flow past the needle, and a second position wherein the needle is biased against the seat, precluding fuel flow past the needle. The fuel injector also includes a multi-layer orifice plate assembly located at the housing outlet. The orifice plate assembly includes a first orifice plate having a plurality of first openings extending therethrough, a second orifice plate having a plurality of second openings extending therethrough and in communication with the first openings, and a third orifice plate located between the first orifice plate and the second orifice plate. The third orifice plate is separate from the first and second orifice plates. The third orifice plate includes an outer perimeter and a plurality of radial channels extending from the outer perimeter toward the longitudinal axis. The fuel injector also includes an air assist sleeve disposed about the housing proximate the outlet. The air assist sleeve includes at least one air channel in communication with radial channels.
The present invention also provides a method of directing a fuel/air mixture through a fuel injector. The method comprises providing a fuel injector having a housing having an inlet, an outlet, a longitudinal axis extending therethrough, and a seat disposed proximate to the outlet, the seat including a sealing surface and a passage extending therethrough. The fuel injector also includes a needle being reciprocally located within the housing along the longitudinal axis between a first position wherein the needle is displaced from the seat, allowing fuel flow past the needle, and a second position wherein the needle is biased against the seat, precluding fuel flow past the needle. The fuel injector also includes a multi-layer orifice plate assembly located at the housing outlet. The orifice plate assembly includes a first orifice plate having a plurality of first openings extending therethrough and a second orifice plate disposed proximate to the first orifice plate. The second orifice plate includes a first face having a perimeter, a plurality of channels extending radially therethrough from the longitudinal axis toward the perimeter, a second face disposed opposite the first face, and a plurality of second openings extending between the first face and the second face. The fuel injector also includes an air assist sleeve disposed about the housing proximate to the outlet. The air assist sleeve includes at least one air channel in communication with the plurality of channels. The method further comprises directing fuel through the first openings; mixing assist air from the assist air channel with the fuel between the first orifice plate and the second orifice plate, forming a fuel/air mixture; and directing the fuel/air mixture through the second openings.